JP5272368B2 - Coated conductive particles, method for producing coated conductive particles, anisotropic conductive adhesive, and conductive adhesive - Google Patents

Description

  The present invention relates to coated conductive particles having excellent connection reliability, a method for producing coated conductive particles, an anisotropic conductive adhesive, and a conductive adhesive.

  The method of mounting a liquid crystal driving IC on a liquid crystal display glass panel can be broadly classified into two types, COG (Chip-on-Glass) mounting and COF (Chip-on-Flex). In COG mounting, an IC for liquid crystal is directly bonded onto a glass panel using an anisotropic conductive adhesive containing conductive particles. On the other hand, in COF mounting, a liquid crystal driving IC is bonded to a flexible tape having metal wiring, and these are bonded to a glass panel using an anisotropic conductive adhesive containing conductive particles. Anisotropy here means conducting in the pressurizing direction and maintaining insulation in the non-pressurizing direction.

  The conductive particles used here are plated with Au on the surface of the resin core particles, as described in JP-A-61-78069, JP-A-62-165886, JP-A-6-283226, and the like. Are listed. When Au plating is directly performed on the resin core particles, there is a problem in the adhesion between Au and the resin. Therefore, it is common to plate Ni on the surface of the resin core particles and Au plating on the outermost layer. is there. Since Au as an adhesive material is expensive, it is necessary to perform plating as thin as possible. For example, according to Japanese Patent Application Laid-Open No. 2005-197089 filed in recent years, the thickness of Au plating is about 0.04 μm.

In addition, with recent high-definition liquid crystal display, gold bumps, which are circuit electrodes of liquid crystal driving ICs, have narrowed pitch and narrowed area, so that conductive particles of anisotropic conductive adhesive are adjacent to each other. There is a problem that a short circuit occurs between the circuit electrodes. When conductive particles flow out between adjacent circuit electrodes, the number of conductive particles in the anisotropic conductive adhesive captured between the gold bump and the glass panel decreases, and the connection resistance between the opposing circuit electrodes is reduced. There was a problem of rising and causing poor connection. Therefore, in order to solve these problems, there is a tendency in recent years to reduce the amount of conductive particles added.
JP-A-61-78069 Japanese Patent Laid-Open No. Sho 62-165886 JP-A-6-283226 Japanese Patent Laid-Open No. 2005-197089 JP-A-61-77278 JP-A-61-77279 JP-A-9-198916 JP 2000-1333050 A JP 2004-156145 A JP 2005-317270 A

  Since the current conductive particles are Au in the outermost layer, the bonding with gold bumps is physical and extremely weak. Therefore, in recent years, the problem that the conduction resistance increases as the amount of conductive particles added is reduced. In addition, the bonding force between the gold particles and the adhesive is weak, and the conductivity often decreases in various reliability tests. In order to strengthen bonding with gold bumps and the like, a method of coating a low melting point metal on the gold surface has been studied for a long time. Specifically, JP-A-61-77278, JP-A-61-77279, JP-A-9-198916, JP-A-2000-133050, JP-A-2004-156145, JP-A-2005-2005. No. 317270.

  When a low melting point metal is coated on the gold surface, the metal surface melts without applying pressure, and conduction between particles occurs. Therefore, the ability as an anisotropic conductive adhesive is inevitably lowered. Further, since the conductive particles have a complicated structure, it is a serious problem at the manufacturing level that the conductive particles are expensive. An object of the present invention is to provide coated conductive particles, a method for producing coated conductive particles, an anisotropic conductive adhesive, and a conductive adhesive that are particularly excellent in connection reliability.

The present invention relates to the following.
1. Conductive particles having a conductive metal surface, wherein at least a part of the metal surface is coated with a polymer electrolyte, the carboxyl group formed on the metal surface and included in the polymer electrolyte Coated conductive particles, wherein the amino groups are chemically bonded .
2. The coated conductive particles according to claim 1, wherein the polymer electrolyte has a weight average molecular weight of 600 or more.
3. Item 3. The coated conductive particle according to Item 1 or 2, wherein the polymer electrolyte is a polyamine.
4). Item 4. The coated conductive particle according to Item 3, wherein the polyamine is polyethyleneimine.
5. Item 5. The coated conductive particle according to any one of Items 1 to 4, wherein the conductive particle is a metal-coated organic core particle.
6). The carboxyl group formed on the metal surface is formed by treating the conductive particles with a compound having a functional group of mercapto group, sulfide group, or disulfide group before coating with the polymer electrolyte. Item 6. The coated conductive particle according to any one of Items 1 to 5, wherein
7). Item 7. The coated conductive particle according to any one of Items 1 to 6, wherein a polymer electrolyte that is not fixed to the surface of the conductive particle is removed.
8). A step of forming a carboxyl group on the metal surface of the conductive particles having a conductive metal surface, a step of coating at least a part of the metal surface of the conductive particle with a polymer electrolyte having an amino group, and the carboxyl group and The manufacturing method of the covering electroconductive particle which has the process of forming a chemical bond with the said amino group.
9. The step of forming the carboxyl group is obtained by treating the conductive particles having the conductive metal surface with a compound having a functional group of any one of a mercapto group, a sulfide group, and a disulfide group. A method for producing the coated conductive particles according to claim 8.
10. The process of forming the chemical bond is performed by heating and drying the conductive particles coated with the polymer electrolyte. The coated conductive particles according to any one of claims 8 to 9, Production method.
11. Item 8-10, comprising a step of removing the polymer electrolyte not fixed to the surface of the conductive particles between the step of coating with the polymer electrolyte and the step of forming the chemical bond. The manufacturing method of the coated electroconductive particle of any one of these.
12 Item 12. A coated conductive particle produced by the method for producing a coated conductive particle according to any one of Items 8 to 11.
13. Item 13. An anisotropic conductive adhesive obtained by dispersing the coated conductive particles according to any one of Items 1 to 7 and 12 in an adhesive.
14 Item 13. A conductive adhesive obtained by dispersing the coated conductive particles according to any one of Items 1 to 7 and 12 in an adhesive.

  According to the present invention, it is possible to provide coated conductive particles having excellent connection reliability, a method for producing coated conductive particles, an anisotropic conductive adhesive, and a conductive adhesive.

Hereinafter, embodiments of the present invention will be described in detail.
The coated conductive particles of the present invention have a polymer electrolyte on at least a part of the surface of the conductive particles. Usually, the polymer electrolyte functions as an adhesion aid. The coated conductive particles of the present invention can be used for anisotropic conductive adhesives or conductive adhesives. The difference between the anisotropic conductive adhesive and the conductive adhesive is that the anisotropic conductive adhesive has less particle content and conducts only in the pressing direction. Usually, anisotropic conductive adhesives are included in the category of conductive adhesives. The content of particles in the anisotropic conductive adhesive is usually in the range of 0.1 to 30 vol%, preferably in the range of 0.1 to 10 vol%, and the content of the particles in the conductive adhesive is usually 60 to It is in the range of 99.9 vol%, preferably in the range of 80 to 99 vol%.

  The following description will focus on the description of the anisotropic conductive adhesive, but naturally it can be used as a conductive adhesive by increasing the content of particles.

  When the coated conductive particles according to the present invention are used for an anisotropic conductive adhesive, the average particle size of the conductive particles is usually smaller than the minimum distance between the electrodes of the substrate, and there is a variation in the height of the electrodes Is preferably larger than the height variation. The height variation of the electrode means a difference between the maximum height and the minimum height of the electrode. The average particle size of the conductive particles is preferably in the range of 1 to 10 μm, and more preferably in the range of 2.5 to 5 μm. If it is smaller than 1 μm, it tends to cause conduction failure, and if it is larger than 10 μm, it tends to cause insulation failure.

  The conductive particles may be either metal-only particles and organic or inorganic core particles that are metal-coated by a method such as plating. Among them, organic core particles that are metal-coated by plating or the like are preferable. . Although it does not specifically limit as a metal coat | covered by plating etc. Gold, silver, copper, platinum, zinc, iron, palladium, nickel, tin, chromium, titanium, aluminum, cobalt, germanium, cadmium etc. metals, ITO, solder, etc. A metal compound is mentioned. The metal layer may have a single layer structure or a laminated structure including a plurality of layers. In the case of a laminated structure, it is preferable to coat the outermost layer with gold from the viewpoint of corrosion resistance and conductivity.

  Examples of the metal coating method include electroless plating, displacement plating, electroplating, and sputtering. Although the thickness of a metal layer is not specifically limited, The range of 0.005-1.0 micrometer is preferable and the range of 0.01-0.3 micrometer is more preferable. If the thickness of the metal layer is less than 0.005 μm, poor conductivity tends to occur, and if it exceeds 1.0 μm, it is not preferable in terms of cost. The organic core particle is not particularly limited, and examples thereof include acrylic resins such as polymethyl methacrylate and polymethyl acrylate, polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polybutadiene, and polystyrene resins.

In the present invention, the coating with a polymer electrolyte refers to forming a coating with a polymer electrolyte fixed on a metal surface, and examples of the fixing means include chemical bonding and adsorption by electrostatic attraction. .
When the conductive particles have a metal surface such as gold, a hydroxyl group is formed on the metal surface by treatment with a compound having any of a functional group such as a mercapto group, sulfide group, disulfide group or the like that forms a coordinate bond with the metal. A carboxyl group, an alkoxyl group, an alkoxycarbonyl group, or the like may be formed. This facilitates the subsequent polymer electrolyte treatment. Specific examples of these compounds include mercaptoacetic acid, 2-mercaptoethanol, methyl mercaptoacetate, mercaptosuccinic acid, thioglycerin, and cysteine.

  The method for treating the metal surface with the above compound is not particularly limited. For example, a compound having the above functional group such as mercaptoacetic acid is dispersed in an organic solvent such as methanol or ethanol to form a solution. The treatment is performed by dispersing conductive particles having a metal surface therein. The surface potential (zeta potential) of the conductive particles having a hydroxyl group, a carboxyl group, an alkoxyl group, or an alkoxycarbonyl group is usually negative (if the pH is neutral). Thereby, the polymer electrolyte is coated on the conductive particles. As a more specific production method, conductive particles having functional groups are dispersed in a polymer electrolyte solution, the polymer electrolyte is adsorbed on the surface of the conductive particles, and then the surface of the conductive particles, such as a rinsing step, is used. Conductive particles whose surfaces are coated with the polymer electrolyte can be produced by performing a process of removing the polymer electrolyte that is not chemically bonded or electrostatically adsorbed to the substrate and is not fixed. Examples of the removing step include cleaning with an aqueous medium such as ultrapure water, rinsing, and the like. By this removal step, the polymer electrolyte not having a coating can be removed from the surface of the conductive particles.

  The polymer electrolyte solution used in the present invention is obtained by dissolving a polymer electrolyte in water or a mixed solvent of water and a water-soluble organic solvent. Examples of water-soluble organic solvents that can be used include methanol, ethanol, propanol, acetone, dimethylformamide, acetonitrile, and the like. If there is no problem in dissolving the polymer electrolyte, it is preferable to use water from the viewpoint of cost.

  As the polymer electrolyte, a polymer that is ionized in an aqueous solution and has a charged functional group in the main chain or side chain can be used. Examples of such a polymer electrolyte include a nitrogen-containing polymer electrolyte, and it is particularly preferable to use a polycation. Such polycations generally have a positively charged functional group such as polyamines such as polyethyleneimine (PEI), polyallylamine hydrochloride (PAH), polydiallyldimethylammonium chloride. (PDDA), polyvinyl pyridine (PVP), polylysine, polyacrylamide, and a copolymer containing at least one of them can be used.

  The weight average molecular weight of the polymer electrolyte is preferably 600 or more, and more preferably in the range of 10,000 to 300,000. When the weight average molecular weight is less than 600, the polymer electrolyte hardly adsorbs, and therefore the effect of improving the conductivity tends to be reduced. When the weight average molecular weight exceeds 300000, the particles tend to aggregate.

  Among the polymer electrolytes, polyethyleneimine and polyallylamine are preferable because of their high charge density and strong bonding strength. In the case of polyethyleneimine, the ratio of C and N is preferably 2: 1, and in the case of polyallylamine, the ratio of C and N is preferably 3: 1.

  In the present invention, for example, a polycation film adsorbed by electrostatic attraction can be obtained by immersing a polymer electrolyte (polycation) having a positive charge in conductive particles having a negative charge. Electrostatic attractive force causes the film to grow by attracting the charge formed on the conductive particles and the material with the opposite charge in the solution, so if the adsorption proceeds and neutralization of the charge occurs, further adsorption Will not occur. Therefore, when reaching a certain saturation point, the film thickness does not increase any more.

  In addition, by alternately immersing the cationic polymer electrolyte and the anionic polymer electrolyte, a thick film made of the cationic polymer electrolyte and the anionic polymer electrolyte can be formed in the form of particles. Such a method is called an alternating lamination method (Layer-by-Layer assembly). The alternate lamination method is described in G.H. This is a method of forming an organic thin film published in 1992 by Decher et al. (Thin Solid Films, 210/211, p831 (1992)). In this method, a polycation adsorbed on a substrate by electrostatic attraction by alternately immersing the base material in an aqueous solution of a polymer electrolyte having a positive charge (polycation) and a polymer electrolyte having a negative charge (polyanion). A combination of polyanions is laminated to obtain a composite film (alternate laminated film). In this case, since the thickness of the composite film can be increased, the adhesiveness is improved.

  By heating and drying the coated conductive particles completed as described above, the bond between the polymer electrolyte and the conductive particles can usually be strengthened. The reason why the binding force is increased includes a chemical bond between the polymer electrolyte and a functional group on the metal surface of the conductive particles. Examples of such a chemical bond include a functional group such as a carboxyl group on the metal surface and a polymer. The chemical bond of the amino group contained in electrolyte is mentioned. The temperature for heating and drying is preferably 60 ° C to 200 ° C, and the heating time is preferably in the range of 10 to 180 minutes. When the temperature is lower than 60 ° C. or when the heating time is shorter than 10 minutes, the insulator particles (polymer electrolyte) easily peel off, and when the temperature is higher than 200 ° C. or the heating time is longer than 180 minutes, the conductive particles. Is not preferred because it is easily deformed.

  The coated conductive particles produced as described above are dispersed in an adhesive to obtain an anisotropic conductive adhesive or a conductive adhesive.

  As the adhesive used for the anisotropic conductive adhesive and the conductive adhesive, for example, a mixture of a heat-reactive resin and a curing agent is used. The adhesive preferably used is a mixture of an epoxy resin and a latent curing agent. Examples of the latent curing agent include imidazole series, hydrazide series, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt, dicyandiamide, and the like. In addition, for the adhesive, a mixture of a radical reactive resin and an organic peroxide, an energy ray curable resin such as an ultraviolet ray, or the like is used.

Epoxy resins used in the present invention include bisphenol type epoxy resins derived from epichlorohydrin and bisphenol A, F, AD, etc., epoxy novolac resins derived from epichlorohydrin and phenol novolac or cresol novolac, and skeletons containing a naphthalene ring. It is possible to use various epoxy compounds having two or more glycidyl groups in one molecule such as naphthalene type epoxy resin, glycidylamine, glycidyl ether, biphenyl, alicyclic, etc. Is possible. For these epoxy resins, it is preferable to use a high-purity product in which impurity ions (Na ⁺ , Cl ^−, etc.), hydrolyzable chlorine and the like are reduced to 300 ppm or less, in order to prevent electromigration.

  In order to reduce the stress after bonding or to improve the adhesiveness, butadiene rubber, acrylic rubber, styrene-butadiene rubber, silicone rubber, or the like can be mixed in the adhesive. Further, as the adhesive, a paste or film is used. In order to form a film, it is effective to blend a thermoplastic resin such as a phenoxy resin, a polyester resin, or a polyamide resin. These film-forming polymers are also effective in stress relaxation when the reactive resin is cured. In particular, when the film-forming polymer has a functional group such as a hydroxyl group, the adhesiveness is improved, which is more preferable. For film formation, an adhesive composition comprising at least an epoxy resin, acrylic rubber, and a latent curing agent is liquefied by dissolving or dispersing in an organic solvent, applied onto a peelable substrate, and below the activation temperature of the curing agent. This is done by removing the solvent. The solvent used at this time is preferably an aromatic hydrocarbon-based and oxygen-containing mixed solvent because the solubility of the material is improved.

  The thickness of the film-like anisotropic conductive adhesive is relatively determined in consideration of the particle size of the conductive particles and the characteristics of the anisotropic conductive adhesive, but is preferably 1 to 100 μm. If it is less than 1 μm, sufficient adhesion tends to be difficult to obtain, and if it exceeds 100 μm, a large amount of conductive particles tend to be required to obtain conductivity. From such a background, a more preferable thickness is 3 to 50 μm.

A method for producing a connection structure using the anisotropic conductive adhesive thus produced will be described with reference to FIG.
FIG. 1A shows an anisotropic conductive adhesive in which coated conductive particles are dispersed in an adhesive 3. Usually, the coated conductive particles are composed of the conductive particles 2 and the polymer electrolyte 1. Next, as shown in FIG.1 (b), the 1st board | substrate 4 and the 2nd board | substrate 6 are prepared, and an anisotropic conductive adhesive is arrange | positioned among them. At this time, the first electrode 5 and the second electrode 7 are opposed to each other. Next, as shown in FIG. 1C, the first substrate 4 and the second substrate 6 are stacked while being heated under pressure. Examples of the substrate include a glass substrate, a tape substrate such as polyimide, a bare chip such as a driver IC, and a rigid package substrate.

  When the connection structure is produced in this manner, the polymer electrolyte functions as an adhesive component, and thus the conduction in the vertical direction is improved. Further, since the polymer electrolyte is firmly bonded to the bulk adhesive, it is fixed in the resin and reliability is increased.

(Conductive particles A (reference))
By forming a nickel layer having a thickness of 0.2 μm on the surface of the crosslinked polystyrene particles having an average particle size of 3.5 μm by electroless plating and further providing a gold layer having a thickness of 0.04 μm outside the nickel, the conductive particles A Was made.

(Coated conductive particles 1)
A reaction liquid was prepared by dissolving 8 mmol of mercaptoacetic acid in 200 ml of methanol. Next, 1 g of conductive particles A was added to the reaction solution, and the mixture was stirred with a three-one motor and a stirring blade having a diameter of 45 mm at room temperature (25 ° C.) for 2 hours. After washing with methanol, the conductive particles were filtered with a membrane filter (manufactured by Millipore) having a diameter of 3 μm to obtain 1 g of conductive particles having a (thio) carboxyl group on the surface.

  Next, a 30% polyethyleneimine P-70 solution (manufactured by Wako Pure Chemical Industries, Ltd .: product name) having a weight average molecular weight of about 70,000 was diluted with ultrapure water to obtain a 0.3 wt% polyethyleneimine aqueous solution. 1 g of the conductive particles having a carboxyl group was added to a 0.3 wt% polyethyleneimine aqueous solution and stirred at room temperature (25 ° C.) for 15 minutes. Next, the conductive particles were filtered through a membrane filter (manufactured by Millipore) having a diameter of 3 μm, put in 200 g of ultrapure water, and stirred at room temperature (25 ° C.) for 5 minutes. Further, the conductive particles were filtered with a membrane filter (manufactured by Millipore) having a diameter of 3 μm, and washed with 200 g of ultrapure water on the membrane filter to remove unimsorbed polyethyleneimine. Thereafter, drying was performed under conditions of 80 ° C. for 30 minutes, and the coated conductive particles 1 were produced by heating and drying at 120 ° C. for 1 hour.

(Coated conductive particles 2)
Instead of 30% polyethyleneimine P-70 solution with a weight average molecular weight of about 70,000 (product name), dilute polyethyleneimine with an average molecular weight of about 10,000 (product name) with ultrapure water. The coated conductive particles 2 were prepared in the same manner as the coated conductive particles 1 except that a 0.3 wt% polyethyleneimine aqueous solution was obtained.

(Coated conductive particles 3)
A polyethyleneimine average molecular weight of about 600 (manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with ultrapure water instead of a 30% polyethyleneimine P-70 solution having a weight average molecular weight of about 70,000 (manufactured by Wako Pure Chemical Industries, Ltd .: product name). The coated conductive particles 3 were produced in the same process as the coated conductive particles 1 except that a 3% by weight polyethyleneimine aqueous solution was obtained.

(Coated conductive particles 4)
Instead of a 30% polyethyleneimine P-70 solution having a weight average molecular weight of about 70,000 (Wako Pure Chemical Industries, Ltd .: product name), Poly (diallydimethylammonium chloride) having a weight average molecular weight of 100,000 to 200,000 (ALDRIC)
Coated conductive particles 4 were produced in the same manner as the coated conductive particles 1 except that H brand: trade name) was diluted with ultrapure water to obtain a 0.3 wt% polydiallyldimethylammonium chloride aqueous solution. .

(Coated conductive particles 5)
Instead of a 30% polyethyleneimine P-70 solution having a weight average molecular weight of about 70,000 (made by Wako Pure Chemical Industries, Ltd .: product name), Poly (allylamine hydrochloride) having a weight average molecular weight of about 70,000 (product name) is ultrapure water. The coated conductive particles 5 were produced in the same manner as the coated conductive particles 1 except that the aqueous solution was diluted with 0.3 to obtain a 0.3% by weight polyallylamine hydrochloride aqueous solution.

(Coated conductive particles 6)
Instead of preparing a reaction solution by dissolving 8 mmol of mercaptoacetic acid in 200 ml of methanol, coated conductive particles were coated in the same manner as coated conductive particle 1 except that 8 mmol of mercaptoacetate was dissolved in 200 ml of methanol to prepare a reaction solution. 6 was produced.

(Coated conductive particles 7)
Instead of preparing a reaction solution by dissolving 8 mmol of mercaptoacetic acid in 200 ml of methanol, the coated conductivity is the same as that of the coated conductive particle 1 except that a reaction solution is prepared by dissolving 8 mmol of 2-mercaptoethanol in 200 ml of methanol. Particle 7 was produced.

(Coated conductive particles 8)
The coated conductive particles 8 were produced in the same process as the coated conductive particles 1 except that the step of forming a carboxyl group on the surface of the conductive particles 1 was omitted.

(Conductive particles 9 (reference))
A 30% polyethyleneimine P-70 solution having a weight average molecular weight of about 70,000 (manufactured by Wako Pure Chemical Industries, Ltd .: product name) was diluted with ultrapure water to obtain a 0.3 wt% polyethyleneimine aqueous solution, and then a conductive group having a carboxyl group. 1 g of conductive particles is added to a 0.3% by weight polyethyleneimine aqueous solution, stirred at room temperature (25 ° C.) for 15 minutes, and the conductive particles are filtered through a φ3 μm membrane filter (Millipore) and put in 200 g of ultrapure water. After stirring at room temperature (25 ° C) for 5 minutes, the conductive particles are filtered through a membrane filter (manufactured by Millipore) with a diameter of 3 µm, and washed twice with 200 g of ultrapure water on the membrane filter. The electroconductive particle 9 was produced in the process similar to the covering electroconductive particle 1 except having omitted the process of removing the polyethyleneimine which is not.

Example 1
The obtained coated conductive particles 1 were dispersed in the following adhesive solution (9% by volume with respect to the adhesive), and this solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater. An anisotropic conductive adhesive film having a thickness of 25 μm was produced by drying at 90 ° C. for 10 minutes.
Preparation of adhesive solution: copolymer of 100 g of phenoxy resin (trade name, PKHC, manufactured by Union Carbide), acrylic rubber (40 parts by weight of butyl acrylate, 30 parts by weight of ethyl acrylate, 30 parts by weight of acrylonitrile, 3 parts by weight of glycidyl methacrylate) , Molecular weight: 850,000) 75 g was dissolved in 400 g of ethyl acetate to obtain a 30 wt% solution.

  Next, 300 g of a liquid epoxy (Eboxy equivalent 185, manufactured by Asahi Kasei Epoxy Co., Ltd., NovaCure HX-3941) containing a microcapsule-type latent curing agent was added to this solution and stirred to prepare an adhesive solution. Next, using the produced anisotropic conductive adhesive film, a chip (1.7 × 17 mm, thickness: 0.5 μm) with gold bumps (area: 30 × 90 μm, space: 30 μm, height: 15 μm, bump number: 200) ) And a glass substrate with an Al circuit (thickness: 0.7 mm) were connected as shown below. After an anisotropic conductive adhesive film (2 × 19 mm) was attached to a glass substrate with an Al circuit at 80 ° C. and 0.98 MPa (10 kgf / cm 2), the separator was peeled off, and the bumps of the chip and the glass substrate with an Al circuit Alignment was performed. Next, the main connection was performed by heating and pressing from above the chip under the conditions of 190 ° C., 40 g / bump, and 10 seconds.

(Example 2)
A sample was prepared in the same manner as in Example 1 except that the coated conductive particles 2 were used instead of the coated conductive particles 1.

(Example 3)
A sample was prepared in the same manner as in Example 1 except that the coated conductive particles 3 were used instead of the coated conductive particles 1.

Example 4
A sample was prepared in the same manner as in Example 1 except that the coated conductive particles 4 were used instead of the coated conductive particles 1.

(Example 5)
A sample was prepared in the same manner as in Example 1 except that the coated conductive particles 5 were used instead of the coated conductive particles 1.

(Example 6)
A sample was prepared in the same manner as in Example 1 except that the coated conductive particles 6 were used instead of the coated conductive particles 1.

(Example 7)
A sample was prepared in the same manner as in Example 1 except that the coated conductive particles 7 were used instead of the coated conductive particles 1.

(Example 8)
A sample was prepared in the same manner as in Example 1 except that the coated conductive particles 8 were used instead of the coated conductive particles 1.

(Comparative Example 1)
A sample was prepared in the same manner as in Example 1 except that the conductive particles A were used instead of the coated conductive particles 1.

(Comparative Example 2)
A sample was prepared in the same manner as in Example 1 except that the conductive particles 9 were used instead of the coated conductive particles 1.

(Insulation resistance test and conduction resistance test)
The insulation resistance test and conduction resistance test of the samples produced in Examples 1-8 and Comparative Examples 1-2 were performed. It is important that the anisotropic conductive adhesive film has high insulation resistance between the chip electrodes and low conduction resistance between the chip electrode / glass electrode. Ten samples of the insulation resistance between the chip electrodes were measured, and the minimum value was measured. Further, the yield was calculated when the conduction resistance> 10 ⁹ (Ω) was a non-defective product. Further, regarding the conduction resistance between the chip electrode and the glass electrode, an average value of 28 samples was measured. The conduction resistance was measured by an initial value and a value after a hygroscopic heat resistance test (standing for 250 hours, 500 hours, and 1000 hours under conditions of an air temperature of 85 ° C. and a humidity of 85%). The measurement results are shown in Table 1 and FIG.

  As shown in Table 1, the samples prepared according to the present invention (Examples 1 to 8) were electrically conductive while maintaining the same level of insulation as compared with the conventional conductive particles (Comparative Examples 1 and 2). It was found that can be improved. In addition, as shown in FIG. 2, it can be seen that in Examples 1 to 8, an increase in conduction resistance with the passage of time is suppressed as compared with Comparative Examples 1 and 2, and deterioration in conductivity can be suppressed. Moreover, when Example 1 and Example 8 are contrasted, the effect which formed the carboxyl group on the electroconductive particle surface is seen. Example 8 to which only the polymer electrolyte was attached had a relatively high conduction resistance. If there is no carboxyl group, the polymer electrolyte is considered to be easily detached. Further, when Examples 1 to 3 are compared, the effect is large when a polymer electrolyte having a large molecular weight is used. Moreover, since Example 1 has a conduction | electrical_connection resistance lower than Example 4 or Example 5, it turns out that a polyethyleneimine has a high effect in a polymer electrolyte. It is considered that the cationic polymer electrolyte is inserted between the metals, so that the bonding property between the metals is increased and the conductivity is improved. In this case, since the average thickness of the polymer electrolyte is 0.1 mm or less, the conductivity is not adversely affected. Moreover, since it has a functional group on the surface of the metal particles, the effect of increasing the reliability by fixing the conductive particles to the adhesive resin can be obtained.

  As described above, according to the present invention, the conductivity of the conductive particles can be improved at low cost by covering at least a part of the surface of the conductive particles having a conductive metal surface with the polymer electrolyte.

It is sectional drawing which shows the manufacturing method of the connection structure using an anisotropic conductive adhesive. It is a graph showing the relationship between the conduction | electrical_connection resistance and elapsed time in an Example and a comparative example.

Explanation of symbols

1: Polymer electrolyte 2: Conductive particles 3: Adhesive 4: First substrate 5: First electrode 6: Second substrate 7: Second electrode

Claims (14)

Conductive particles having a conductive metal surface, wherein at least a part of the metal surface is coated with a polymer electrolyte, the carboxyl group formed on the metal surface and included in the polymer electrolyte Coated conductive particles, wherein the amino groups are chemically bonded .   The coated conductive particles according to claim 1, wherein the polymer electrolyte has a weight average molecular weight of 600 or more.   The coated conductive particle according to claim 1, wherein the polymer electrolyte is a polyamine.   4. The coated conductive particle according to claim 3, wherein the polyamine is polyethyleneimine. The coated conductive particles according to any one of claims 1 to 4, wherein the conductive particles are obtained by metal-coating organic core particles. The carboxyl group formed on the metal surface is formed by treating the conductive particles with a compound having a functional group of mercapto group, sulfide group, or disulfide group before coating with the polymer electrolyte. The coated conductive particles according to any one of claims 1 to 5, wherein the coated conductive particles are any of the above. The coated conductive particle according to any one of claims 1 to 6, wherein a polymer electrolyte not fixed to the surface of the conductive particle is removed. A step of forming a carboxyl group on the metal surface of the conductive particles having a conductive metal surface, a step of coating at least a part of the metal surface of the conductive particle with a polymer electrolyte having an amino group, and the carboxyl group and The manufacturing method of the covering electroconductive particle which has the process of forming a chemical bond with the said amino group. The step of forming the carboxyl group is obtained by treating the conductive particles having the conductive metal surface with a compound having a functional group of any one of a mercapto group, a sulfide group, and a disulfide group. Item 9. A method for producing coated conductive particles according to Item 8. The coated conductive particles according to claim 8, wherein the step of forming the chemical bond is performed by heating and drying the conductive particles coated with the polymer electrolyte. Manufacturing method. 9. A step of removing the polymer electrolyte that is not fixed to the surface of the conductive particles between the step of coating with the polymer electrolyte and the step of forming the chemical bond. 10. The method for producing coated conductive particles according to any one of 10 above. The coated electroconductive particle manufactured by the manufacturing method of the coated electroconductive particle of any one of Claims 8-11. An anisotropic conductive adhesive obtained by dispersing the coated conductive particles according to any one of claims 1 to 7 and 12 in an adhesive. The conductive adhesive formed by disperse | distributing the covering electroconductive particle of any one of Claims 1-7 and 12 to an adhesive agent.

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